Perfect Storms (2013)

S6E19 What Ever Happened to SpongeBob?

SpongeBob sets out to enjoy some quality time with his pals, but his efforts only lead to him becoming an annoyance. Frustrated, he decides to leave and start fresh in a different city. However, during his journey, he accidentally bumps his head, causing him to lose all his memories. As a result, he finds himself aimlessly wandering through a new town, completely unaware of his past.